CX3CR1 is a G-protein coupled integral membrane protein, which is a chemokine receptor. It is predominantly expressed on cell types such as monocytes, dendritic cells and T cells that have been associated with the initiation and progression of atherosclerotic plaques. It is upregulated on monocytes by oxidized lipids and mediates migration of these cells into and survival within plaques. Its unique ligand fractalkine (FKN) is expressed on the surface of vascular endothelial and smooth muscle cells in lesions where it modulates leukocyte adhesion. Fractalkine is also released into the circulation by proteolytic cleavage where it functions as a chemotactic agent.
In humans, a CX3CR1 variant (V249I/T280M) with decreased activity has been shown to be associated with a lower risk of cardiovascular disease (coronary heart disease, cerebrovascular disease or peripheral vascular disease) (McDermott, 2001; Circ Res 89:401), coronary artery disease (angiographic evidence of stenosis) (McDermott, 2003; J. Clin. Invest. 111:1241), and carotid artery occlusive disease (Ghilardi, 2004; Stroke 35:1276). CX3CR1 co-localized with fractalkine which showed enhanced immunostaining by polyclonal antibodies within atherosclerotic plaques (Wong, 2002 Cardiovasc. Path. 11:332). No fractalkine staining was observed in non-plaque arterial regions.
Several independent mouse genetic studies have shown a beneficial effect of CX3CR1 deficiency on atherosclerosis. A reduction in lesion area in the aortic arch and thoracic aorta as well as a decrease in monocyte/macrophage accumulation in plaques was seen in two independently derived strains of CX3CR1−/− apoE−/− mice fed a high fat diet (Combadière, 2003; Circulation, 107:1009, Lesnik, 2003; J. Clin. Invest. 111:333).
This shows that CX3CR1 is involved in cardiovascular diseases and the modulation of its activity could provide promising therapies. There is therefore a need for antagonist molecules against CX3CR1 with beneficial pharmacological properties, which can be used as therapeutic agents to treat diseases, in particular cardiovascular diseases in humans.
Accordingly, one aim of the present invention is to provide anti-CX3CR1 antagonist molecules, in particular anti-CX3CR1 antagonist molecules, which have high binding affinity to CX3CR1.
A further aim of the present invention is to provide anti-CX3CR1 antagonist molecules, which have high specificity for CX3CR1.
A further aim of the present invention is to provide anti-CX3CR1 antagonists, which have potent activity.
A further aim of the present invention is to provide anti-CX3CR1 antagonists, which have a favorable bioavailability and half-life.
A further aim of the present invention is to provide anti-CX3CR1 antagonists, which have favorable biophysical properties.
Further aims of the present invention include combinations of any of the aims set forth above.